I don't think that KVN's chatur raga pallavi is commercially available. But you can find 3 to 4 concerts in sangeethapriya.org where KVN has rendered that pallavi. Below is one among those with LJ and Palghat Raghu,

Don't have KVNs famous pallavi "Sankarabarananai Azhaithodi Vadi Kalyani Darbaruruku" Where the pallavi is sung in 4 different ragas but TM Krishna's same pallavi is enjoyed in my house almost everyday by my 10 yr old son.... love that CD.

Neraval is one of the important aspect in a concert. Neraval or sahitya prastara is where a musician takes a line from a krithi and renders the same line with various variations and should also keep it with in the tala. This is something which cannot be taught it is only with pure manodharmam and Gnanam. Usually Neraval line will be a charanam of a krithi.

I have heard semmangudi singing Neraval in " Booloka Vaikunda Mithiyani" in O rangasayee in the raga kambodhi. When it comes to neraval there is one name which every musicians will remember K.V.Narayanaswamy. He sings neraval with so much bhakthi and bhavam. You can feel the vibrations in many neraval rendition of KVN. My favourite is " Annai Kamatchipola Anbe Vadivai Vandhai" in the Krithi Punniyam Oru Koti composed by periyaswamy thooran in the raga kiravani.

Neraval Singing is also an important aspect in RTP's.My favourite neraval in RTP is again by KVN in the famous pallavi "Sankarabarananai Azhaithodi Vadi Kalyani Darbaruruku" Where the pallavi is sung in 4 different ragas . KVN's neraval is a pure display of manodharma and his raga variation form one to another is truly brilliant.